Two factors to consider id say. Blood isn't the only organic source of nitrogen so it's not as if its necessary, thus I'd wager many vegans would consider it unnecessary animal suffering, at least in theory. However the caveat, and second factor, would be blood is byproduct, no ones killing the animals in order to obtain blood meal so many people including vegans may think it more ethical to not let it go to waste since weather or not there's a demand for blood meal, there will still be animal blood that needs to be disposed of.
Strictly dietarialy, yes they would still be vegan. All soil is full of countless formless decomposed animals and plants, it's an inescapable reality of how the soil came to be. It can only get more ethically involved when you choose to add it yourself imo.
That second point would require intimate knowledge about which animal parts would be disposed of if they didn't find a buyer.
In reality, everything is used. If there wasn't a market for part of an animal, a use was found and a market created (which is part of the reason why industrially produced white sugar, beer, wine, apple juice, potato chips and bread usually aren't vegan).
Anyway, vegans usually don't care about whether an animal product could be leftover. Their philosophy boils down to "Just fucking leave animals in peace."
Even honey isn't okay with some (I have no idea the %, could be most or just a small number) of vegans. So regardless of how the blood was obtained, there is at least some who would not consider it vegan.
There are vegan blood meal alternatives out there to resolve this exact conundrum.
But the reality is, unless your plants are being grown hydroponically in a sealed warehouse or similar, chances are real good that they are feeding on decaying animals (either directly or indirectly) whether you like it or not. They're mostly insects and annelids and such, but still animals.
I think the issue for vegans is more about whether animal slaughter was involved in making their fertilizer. Dead pillbugs in the soil is just nature doing its cycle of life thing.
Also it's good to let people know because dogs absolutely love that shit and you have to be careful to keep it out of areas dogs can get at it.
I worked in a green house and one customer's dog dug up an entire tree she planted to get at the blood meal she put in the bottom of the hole. Dog was okay, but needed to stay at the vets a few days to monitor the vomiting and their iron levels.
Stuff is expensive. It's the best thing I've found for keeping deer from eating my plants, but then I got a dog that just went nuts for the stuff and would just eat it like mad when he went outside. So now the dear just eat my plants again.
Our dachshund picks up and eats all kind of shit. She's a destroyer of SHOES and CPAP masks, of course, but she also eats rocks, plastic, or whatever else she finds.
The other day I walk in, and she has 2 milkbones (we don't buy them and I have no idea where they came from). She just moved them around for a few days and never ate them. But a stick is fine dining.
The way dogs handle new food is interesting. They have very short digestive tracts so the idea for them is to eat everything once, and if it makes them sick it will make them sick very quickly. They then know not to eat something.
Thats a possible reason for the aversion. They can also associate foods with traumatic events sort of like humans do.
This is what I came here to say. The clarification on the post is not about humans eating plant food, it's about idiot fucking pets eating plant food. They eat grass, why wouldn't they chow down on something that smells like blood.
Ahh, that says you might need ~2.3 kg of iron sand after removing the non-iron from the material. Blood meal appears to be .2% iron by weight. Very napkin quality math says you'd need ~1150 bags to get enough iron
I feel like the tumblr user asking why it's necessary to tell people not to eat blood meal must have forgotten they're on tumblr. The whole site is just smut curated by the generation that turned eating tide pods into a meme.
Meat is red because of myoglobin, a protein found in mammalian muscle tissue that turns red when exposed to oxygen.
Myoglobin is different from hemoglobin though, which is the stuff in blood. Most of the time, your meat only has a tiny amount of hemoglobin in it by the time it gets to your table.